Such a spindle drive is known from U.S. Pat. No. 5,222,402. In this case, the spindle is motor-driven, the nut unit is stationary. The invention preferably relates to a spindle drive in which the spindle is actively motor-driven. With regard to the prior art, reference is also made to DE 1 755 740 A1, WO 86/06036, U.S. Pat. No. 6,260,922 B1 and U.S. Pat. No. 7,340,974 B2. In these known spindle drives, the nut unit is actively driven.
Nuts made from plastic are already known; in this regard, reference is made to the above-mentioned WO 86/06036. It shows a nut made from hard plastic comprising an outer jacket limited by a cylinder. In the generic U.S. Pat. No. 5,222,402, which describes a motor drive of the spindle, the cross section of the nut, in contrast, is rectangular, and the inner space of a lower rail of the longitudinal adjustment device forms the retainer, i.e., a non-rotatable accommodation of this nut. In this case, assembly entails a lot of effort because the drive, and thus the spindle, is allocated to the upper rail, but the output with the nut unit is allocated to the lower rail. Advantageously, the protected arrangement in this case lies within a channel limited by the two rails.
A universal use of spindle drive is desirable. Preferably, they are configured as ready-to-use assembly units. They have two assembly areas at which they are connected with the parts that are to be adjusted relative to each other.